Squid
2 of the 7 encyclopedias on this shelf carry an entry for Squid. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a marine animal allied to the cuttlefish. The calamar, or squid, has ten arms, two of which are longer than the others. The body is elongated and tapers toward the posterior end. Near the posterior end are two fin-like flaps of skin, one on each side. Inside the body is a narrow, pen-shaped shell, which is somewhat horny but very easily bent. The squid, like the cuttlefish, is able to squirt a dark colored fluid about in the water, to the confusion of its enemies. It lives in temperate as well as in warm regions of the ocean. It is represented by several groups of species. The smallest squid is not to exceed an inch in length. The giant squid has an arm spread of fifty feet. The common squid reaches a length of two feet or more. It is bluish or purple in color. In the Mediterranean is found a species which, when full-grown, is about ten inches in length, and white, almost transparent in color. When frightened or captured it assumes a delicate pink or rose color, the tints being deepest over its back or dorsal side. The fins are used in swimming rapidly through the water, and it seems a creature of almost unearthly beauty, so delicate is its form and color. Squids are found in great numbers along both shores of North America . All squids are fish eaters. They hunt at night; darting backward into a school of mackerel like arrows, they create havoc. See Cuttlefish ; Octopus
Collier's New Encyclopedia (1921)
a popular name of certain cuttle fishes belonging to the dibranchiate group of the class Cephalopoda, and included in several genera, of which the most familiar is that of the calamaries.